Various optical scanning devices, such as, for example, 2-D scanners or imaging scanners, have been developed for reading barcode symbols appearing on a label or the surface of an article. The barcode symbol itself is a coded pattern of indicia comprised of a series of bars of various widths spaced apart from one another to bound spaces of various widths. The bars and spaces have different light-reflecting characteristics and the barcode is read by projecting light, such as that from a laser beam, onto the barcode. The information content of the bar code is retrieved by monitoring the reflected beam and converting modulation in the reflected light in to a signal corresponding to the symbols.
Typically, the scanner has a body to house the components and a window to permit transmission of the beam from the laser and receive the reflected portion of the beam, The accuracy and range of the scanning device depends in part on the quality of the transmission through the window and any obstruction will lead to a degradation in performance.
Many optical scanning devices are mobile for use in warehousing and similar environments where a variety of environmental conditions can exist in a short span of time. For example, a hand-held barcode reader may be used to inventory goods located in a freezer. To avoid undue exposure of the operator to low temperatures, the frozen goods are withdrawn from the freezer and inventoried outside the freezer. When the hand-held barcode reader is taken in to a cold environment, the temperature of it's components drops below the dew point and, upon return to room temperature, condensation builds up on either or both sides of the barcode reader's window. The condensation completely or partially obscures the window and thus reduces the effectiveness of the barcode reader until the condensation dissipates. This leads to either inaccuracy of the reading or a reduction in the efficiency of the inventory taking.
Accordingly, it is an object of the present application to obviate or mitigate the above disadvantages.